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African Horse Sickness, unnamed (1), image033-1, YHPHHR2HCHXLEZRLEZRL9ZML9…
African Horse Sickness
Etiology
Orbivirus
9 serotypes
Endemic in
central tropical region of Africa
Recently (April 2020) reported in Thailand - imported zebras from Africa
Mortality % in horses: 70-95%
In zebras and African donkeys, subclinical infection occurs and viremia can extend up to 40 days
Hosts:
Equids
(Horses, donkeys, mules and
zebras- reservoir
)
Dogs ingested infected horsemeat will get peracute fatal infection
Sources of virus:
Viscera and blood of infected animals
Semen, urine, other secretions during viremia
Recovered animals do not maintain as carriers
Mode of transmission
Biological vectors
(Moist and warm condition)
Culicoides imicola
Culicoides bolitinus
Rhipicephalus sanguineus
Hyalomma dromedarii
Stomoxys spp
Tabanus spp
Ingestion of infected equid
Clinical signs
Pulmonary form
Fever
Dyspnea
Spasmodic coughing
Dilated nostrils
Acute respiratory form (after 3-5 days)
Animal stands with its legs apart and head extended
Cardiac form
Swelling extend to the eyelids, facial tissues, neck, thorax, brisket, and shoulders
Progressive dyspnea
Mixed pulmonary and cardiac form
Mild or horse sickness fever form
Low fever
Congested mucous membrane
Postmortem lesion
MECHANISM
Dysfunction and lysis of endothelial cells
Endothelial cell barrier dysfunction
4 clinical forms
Active hyperemia, petechial and ecchymotic hemorrhages
serosal [epicardial, endocardial], subcapsular [spleen]
cortical [kidney], mucosal [intestines]
Edema
pulmonary, systemic, subcutaneous, intramuscular, supraorbital fossae, eyelids, lips, cheeks, tongue, intermandibular space, and larynx
Hydrothorax
Hydropericardium
Ascites
Rhabdomyocytic necrosis
lesser extend
dendritic, lymphoid, and monocyte-macrophage systems
Pathogenesis
Bite wounds from midges (vector)
Capsid structural proteins
(VP2 and VP5) of
(virus)
+
Attach to glycosaminoglycans
of cell membrane
(target)
Deposited in vascularized ECM (connective) tissues
Infect cutaneous dendritic cells (Langerhans cells) and tissue macrophages
Spread via leukocyte trafficking
to regional lymph nodes
Infects lymphocytes and additional dendritic cells and macrophages
1 more item...
Get into cutaneous blood and fluids
CARDIAC FORM / PULMONARY FORM / MIXED
Differential diagnosis
Equine viral arteritis
Trypanosomiasis
Equine infectious anaemia
Equine encephalosis
Anthrax
Piroplasmosis
Purpura hemorrhagica
Hendra virus
Laboratory diagnosis
Virus isolation
Unclotted whole blood collected during early febrile stage sent to lab at 4°C
Spleen, lung and lymph node samples collected from freshy dead animals sent to lab at 4°C (Do not freeze)
Cell cultures:
Baby hamster kidney-21 (BHK-21)
Monkey stable (MS)
African green monkey kidney (Vero)
Insect cells (KC)
Intravenously in embryonated eggs
Intracerebrally in newborn mice
Virus Identification
ELISA- Rapid detection of AHSv in blood, spleen
Virus neutralization- Gold standard!
RT-PCR
Real-time PCR (Detects all 9 serotypes
Serology
Paired serum samples with 21 days apart (Kept frozen at -20°C)
Horses that survived AHS will generate antibodies within 8-12 days
Indirect ELISA
Complement fixation test (CFT)
Prevention and control
Medical
No specific treatment
Treat complication and secondary infections appropriately during recovery
Live-attenuated virus vaccines available (Provide good but not absolute protection)
Annual revaccination is recommended
Management
Rest and good husbandry
Introducing animal movement restrictions
Husbandry modification (eg, stabling in vector-proof housing)
Strict regimens of testing and quarantine when import or export from active country
Incubation period
Pulmonary form
1-2 days
Acute respiratory form: 3-4 days
Cardiac form
1-2 week
PM LESION PHOTOS PLEASE SCAN ME
depends on differences location of viral tropism or replication in
vascular endothelial cells
REFERENCES
Diagnosis and differential diagnosis. (n.d.). Retrieved from
http://www.afrivip.org/sites/default/files/AHS/diagnosis.html
OIE (n.d.). African Horse Sickness. Retrieved April 27, 2020, from
https://www.oie.int/fileadmin/Home/eng/Animal_Health_in_the_World/docs/pdf/Disease_cards/AFRICAN_HORSE_SICKNESS.pdf
McKenna, T. S. C. (2015, October). Overview of African Horse Sickness - Generalized Conditions. Retrieved April 27, 2020, from
https://www.merckvetmanual.com/generalized-conditions/african-horse-sickness/overview-of-african-horse-sickness
Zachary, J. F. (2017). PATHOLOGIC BASIS OF VETERINARY DISEASE (J. F. Zachary (ed.); 6th ed.). Elsevier, 212-214
Peste Equina Africana (2015, Feb). African Horse Sickness. Retrieved April 27, 2020, from file:///C:/Users/weiti/Desktop/african_horse_sickness.pdf
Disease Images: African Horse Sickness. (n.d.). Retrieved April 26, 2020, from
http://www.cfsph.iastate.edu/DiseaseInfo/clinical-signs-photos.php?name=african-horse-sickness
NS3
cytotoxic protein (viroporin)
membrane damage & release virus
Ticks
Mosquitoes
Biting flies
Movement of Culicoides spp:
700km over water and 150km over land
:<3:
BY GROUP 6 DVM 4:
Tan Jia Wen D16A0034
Hong Wei Ting D16A0058
Lavanyah Sunmugam D16A0059
Nur Atiqah bt Md Zamani D16A0028
Yong Kai Yuan D16A0037
Ibtihal Binti Mohammad D16A0014
Emir Izad bin Hashan Arif D16A0011
Jagathis Wee Vanniar Murugapiran D16A0015
